[LargeFormat] Double Protar Lens
Clive Warren
largeformat@f32.net
Thu Sep 4 16:55:08 2003
At 7:20 pm -0400 1/9/03, LNphoto wrote:
Huge Snip
>According to my 1911 catalog, a pair of 11 3/16" cells give a
>combinded focal lenght of 6 3/8" @ f6.3 and covers 4 1/2 x 7 1/4.
>Something tells me in later years that was rounded to 5x7. The 11
>3/16" cell alone will cover 6x8 (whole plate) and has a back focus
>of 12 7/16".
>
>I have a couple of B&L double protars....enough to make a D set. I
>also have C+ set from Zeiss. While the glass may be similar, you
>have to remember these were made with "native" machines.... The
>Zeiss is metric through and through, The B&L is Yankee. The Ross
>may be "stricken" with Whitworth threads, so that tube may need
>different threads at one end than the other.
>
>Les
Les and Richard,
I seem to have become the target of used Protar dealers ;-)
There is now another set winging its way towards sunny Bristol from
the caves of Mordor in the North. This time it is again a set of
same focal length cells, Bausch & Lomb - Zeiss Protar Series VII
Focus 16 1/8" both front and rear cells.
From what you have said, it seems that one of these would have formed
part of a D set? Presumably in a larger diameter barrel than the C
set. Perhaps your catalog has the info. for the combined focal
length..... would be great if the combined lens covers 8x10 however I
have the feeling that you are going to tell me that the combined FL
is around 8".
It seems almost certain that the previous lens is a pair of 11 3/16"
cells as you suggested. The stops are marked in the Unified System
which caused me some confusion initially f:16 = f/16 and work from
there......
Cheers,
Clive